This invention relates to a suction control device in an endoscope, which is used to remove mucus, dirty substance or the like in the human body cavity through an endoscope channel.
Generally, a suction control device in an endoscope serves, in addition to the original function of controlling the sucking out of mucus, dirty substance etc. in the human body cavity, to lead a medical fluid, as well as a medical instrument such as forceps, into the channel of the endoscope. A conventional suction control device for an endoscope comprises, as shown in FIG. 1, a mounting tube 1 provided on the operating section 2 of the endoscope, a hollow cylindrical member 3 tightly fitted into the mounting tube 1 and having its distal end communicating with a corresponding channel of the endoscope, and an inner tube assembly 4 coaxially inserted into the hollow cylindrical member 3. An air chamber 5 is defined by the inner surface of a larger diameter portion of the hollow cylindrical member 3 and outer surface of the inner tube assembly 4 and communicates with the endoscope channel and with a suction tube 6 projecting from the side wall of the hollow cylindrical member 3. A metallic cap 7 is fitted over the proximal end of the hollow cylindrical member 3 and has a central hole 8 communicating with the interior of the inner tube assembly 4. The central hole 8 of the cap 7 is adapted to be blocked by a finger cushion so as to take out through the endoscope channel, mucus, dirty substances etc. in the body cavity of the human being. Since, however, the cap of the conventional control device is made of metal, no sufficient contact is assured between the inner peripheral edge of the central hole 8 of the cap 7 and the finger cushion. In other words, air leaks into the inner pipe assembly 4 from between the inner peripheral edge of the central hole 8 of the cap 7 and the finger cushion, failing to sufficiently remove mucus, dirty substance etc. from the human body cavity. It is a usual practice to operate various levers of the endoscope operating section 2 by the thumb and block the central hole 8 of the cap by the index finger of the same hand. Since, however, the cap 7 lacks flexibility, it is not easy for the user to quickly block the control hole 8 of the cap 7 as required. The mere placement of the index finger over the central hole 8 of the cap 7 is sometimes insufficient to completely block the central hole 8 of the cap 7. Furthermore, where an elongated medical instrument such as forceps is used, the central hole 8 of the cap 7 can not be blocked by the human finger, since the instrument is inserted into the inner pipe assembly 4. As a result, a sucking capability is markedly reduced.